Mattress



FIG. 1 is a front, right, and bottom perspective view of a mattress, showing my design.

FIG. 2 is a front elevation view thereof.

FIG. 3 is a rear elevation view thereof.

FIG. 4 is a left side elevation view thereof.

FIG. 5 is a right side elevation view thereof.

FIG. 6 is a top plan view thereof.

FIG. 7 is a bottom plan view thereof; and,

FIG. 8 is a partial enlarged view of an area labeled 8 in FIG. 7 comprising zippers.

The broken lines framing portions of the claimed design that are illustrated for enlargements form no part of the claimed design. 

CLAIM The ornamental design for a mattress, as shown and described. 